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Data as of 2026-09-20
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Built 2026-09-21 (21 September 2026)

Italy South Demand Forecast Accuracy: Error, Bias and Worst Miss, 23 August to 20 September 2026

The day-ahead demand forecast for Italy South was off by 7.5% on average (mean absolute percentage error) over 686 hours from 23 August to 20 September 2026, and 35% of hours landed within 5% of the reading. Its bias was -1.8%: it ran low on average, an under forecast. The largest miss was 983 MW (22.4%) too low at 25 Aug 2026, 17:00 CEST (UTC+02:00). Dates and times are local (Europe/Rome).

Key Facts

  • The day-ahead demand forecast for Italy South was off by 7.5% on average (mean absolute percentage error) over 686 hours from 23 August to 20 September 2026, and 35% of hours landed within 5% of the reading. Its bias was -1.8%: it ran low on average, an under forecast. The largest miss was 983 MW (22.4%) too low at 25 Aug 2026, 17:00 CEST (UTC+02:00).
  • Across 47 European bidding zones ranked by average error over their own latest 30 day windows, Italy South came 37 (1 is the smallest error).
  • On average the forecast differed from reported demand by 223 MW, against average demand of 2,959 MW.
  • The forecast was above reported demand in 37% of compared hours.

Forecast Error at a Glance

686 hours from 23 August to 20 September 2026
Average error7.5%
Bias-1.8%
Hours within 5%35%
Worst miss983 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-88 MW per hour on average): the forecast ran low on average, an under forecast. The worst miss was 983 MW (22.4%) too low at 25 Aug 2026, 17:00 CEST (UTC+02:00): forecast 3,410 MW, reported 4,392 MW.

Source: ENTSO-E Transparency Platform (transparency.entsoe.eu), CC BY 4.0. Aggregated and converted by World Power Monitor; ENTSO-E does not endorse this site. (ENTSO-E Terms of Use plus CC BY 4.0 for listed data items) Data as of 2026-09-20. Accuracy is computed by World Power Monitor from the operator's hourly forecast and reported demand.

Forecast and Reported Demand, Last 7 Days

Local time, to 20 Sept 2026, 13:00 CEST (UTC+02:00)
Italy South day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for Italy South over the last 7 days of the window, to 20 Sept 2026, 13:00 CEST (UTC+02:00). Gaps are hours with a missing, zero or implausible report. 0 1,000 2,000 3,000 4,000 13 Sept, 14:0014 Sept, 14:0015 Sept, 14:0016 Sept, 14:0017 Sept, 14:0018 Sept, 14:0019 Sept, 14:00
Hourly reported demand and the day-ahead forecast for Italy South over the last 7 days of the window, to 20 Sept 2026, 13:00 CEST (UTC+02:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-09-20
Italy South day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 14:001,839 MW1,995 MW
13 Sept, 15:001,759 MW1,977 MW
13 Sept, 16:001,814 MW2,110 MW
13 Sept, 17:001,978 MW2,323 MW
13 Sept, 18:002,101 MW2,470 MW
13 Sept, 19:002,285 MW2,588 MW
13 Sept, 20:002,386 MW2,613 MW
13 Sept, 21:002,235 MW2,543 MW
13 Sept, 22:002,104 MW2,435 MW
13 Sept, 23:002,051 MW2,355 MW
14 Sept, 00:001,952 MW2,247 MW
14 Sept, 01:001,887 MW2,165 MW
14 Sept, 02:001,822 MW2,103 MW
14 Sept, 03:001,843 MW2,037 MW
14 Sept, 04:001,826 MW2,018 MW
14 Sept, 05:001,878 MW2,118 MW
14 Sept, 06:002,110 MW2,226 MW
14 Sept, 07:002,200 MW2,340 MW
14 Sept, 08:002,195 MW2,447 MW
14 Sept, 09:002,297 MW2,523 MW
14 Sept, 10:002,593 MW2,441 MW
14 Sept, 11:002,550 MW2,438 MW
14 Sept, 12:002,515 MW2,443 MW
14 Sept, 13:002,510 MW2,397 MW
14 Sept, 14:002,264 MW2,413 MW
14 Sept, 15:002,310 MW2,433 MW
14 Sept, 16:002,530 MW2,543 MW
14 Sept, 17:002,729 MW2,668 MW
14 Sept, 18:002,648 MW2,848 MW
14 Sept, 19:002,872 MW2,927 MW
14 Sept, 20:002,888 MW2,910 MW
14 Sept, 21:002,641 MW2,757 MW
14 Sept, 22:002,596 MW2,563 MW
14 Sept, 23:002,392 MW2,375 MW
15 Sept, 00:002,360 MW2,511 MW
15 Sept, 01:002,083 MW2,326 MW
15 Sept, 02:002,021 MW2,325 MW
15 Sept, 03:002,035 MW2,264 MW
15 Sept, 04:002,188 MW2,198 MW
15 Sept, 05:002,345 MW2,274 MW
15 Sept, 06:002,456 MW2,401 MW
15 Sept, 07:002,588 MW2,489 MW
15 Sept, 08:002,497 MW2,607 MW
15 Sept, 09:002,571 MW2,916 MW
15 Sept, 10:002,691 MW3,033 MW
15 Sept, 11:002,812 MW3,057 MW
15 Sept, 12:002,827 MW2,965 MW
15 Sept, 13:002,682 MW2,855 MW
15 Sept, 14:002,728 MW2,686 MW
15 Sept, 15:002,699 MW2,609 MW
15 Sept, 16:002,780 MW2,720 MW
15 Sept, 17:002,917 MW2,949 MW
15 Sept, 18:002,830 MW2,986 MW
15 Sept, 19:002,883 MW3,096 MW
15 Sept, 20:002,834 MW3,006 MW
15 Sept, 21:002,677 MW2,871 MW
15 Sept, 22:002,561 MW2,677 MW
15 Sept, 23:002,362 MW2,535 MW
16 Sept, 00:002,206 MW2,390 MW
16 Sept, 01:002,145 MW2,214 MW
16 Sept, 02:002,104 MW2,217 MW
16 Sept, 03:002,118 MW2,207 MW
16 Sept, 04:002,128 MW2,210 MW
16 Sept, 05:002,143 MW2,331 MW
16 Sept, 06:002,313 MW2,371 MW
16 Sept, 07:002,439 MW2,510 MW
16 Sept, 08:002,451 MW2,618 MW
16 Sept, 09:002,444 MW2,889 MW
16 Sept, 10:002,436 MW3,035 MW
16 Sept, 11:002,569 MW3,052 MW
16 Sept, 12:002,770 MW2,841 MW
16 Sept, 13:002,686 MW2,783 MW
16 Sept, 14:002,533 MW2,681 MW
16 Sept, 15:002,546 MW2,628 MW
16 Sept, 16:002,623 MW2,679 MW
16 Sept, 17:002,887 MW2,890 MW
16 Sept, 18:002,942 MW2,925 MW
16 Sept, 19:002,954 MW3,129 MW
16 Sept, 20:002,842 MW3,083 MW
16 Sept, 21:002,769 MW2,887 MW
16 Sept, 22:002,561 MW2,661 MW
16 Sept, 23:002,381 MW2,550 MW
17 Sept, 00:002,193 MW2,157 MW
17 Sept, 01:002,096 MW2,060 MW
17 Sept, 02:002,135 MW2,010 MW
17 Sept, 03:002,176 MW2,042 MW
17 Sept, 04:002,167 MW2,027 MW
17 Sept, 05:002,207 MW2,081 MW
17 Sept, 06:002,325 MW2,219 MW
17 Sept, 07:002,502 MW2,272 MW
17 Sept, 08:002,608 MW2,281 MW
17 Sept, 09:002,597 MW2,389 MW
17 Sept, 10:002,648 MW2,588 MW
17 Sept, 11:002,702 MW2,615 MW
17 Sept, 12:002,671 MW2,610 MW
17 Sept, 13:002,384 MW2,577 MW
17 Sept, 14:002,233 MW2,285 MW
17 Sept, 15:002,201 MW2,281 MW
17 Sept, 16:002,321 MW2,434 MW
17 Sept, 17:002,720 MW2,606 MW
17 Sept, 18:002,900 MW2,594 MW
17 Sept, 19:003,027 MW2,840 MW
17 Sept, 20:002,824 MW2,825 MW
17 Sept, 21:002,665 MW2,626 MW
17 Sept, 22:002,461 MW2,593 MW
17 Sept, 23:002,323 MW2,390 MW
18 Sept, 00:002,140 MW2,255 MW
18 Sept, 01:001,974 MW2,160 MW
18 Sept, 02:001,903 MW2,125 MW
18 Sept, 03:001,925 MW2,132 MW
18 Sept, 04:001,919 MW2,113 MW
18 Sept, 05:001,971 MW2,193 MW
18 Sept, 06:002,116 MW2,315 MW
18 Sept, 07:002,218 MW2,420 MW
18 Sept, 08:002,310 MW2,478 MW
18 Sept, 09:002,347 MW2,545 MW
18 Sept, 10:002,288 MW2,543 MW
18 Sept, 11:002,282 MW2,623 MW
18 Sept, 12:002,235 MW2,700 MW
18 Sept, 13:002,176 MW2,665 MW
18 Sept, 14:002,330 MW2,627 MW
18 Sept, 15:002,381 MW2,681 MW
18 Sept, 16:002,552 MW2,702 MW
18 Sept, 17:002,704 MW2,835 MW
18 Sept, 18:002,872 MW2,783 MW
18 Sept, 19:003,033 MW2,865 MW
18 Sept, 20:002,933 MW2,840 MW
18 Sept, 21:002,684 MW2,718 MW
18 Sept, 22:002,532 MW2,585 MW
18 Sept, 23:002,382 MW2,375 MW
19 Sept, 00:002,108 MW2,255 MW
19 Sept, 01:001,960 MW2,139 MW
19 Sept, 02:001,910 MW2,112 MW
19 Sept, 03:001,869 MW2,121 MW
19 Sept, 04:001,896 MW2,120 MW
19 Sept, 05:001,942 MW2,152 MW
19 Sept, 06:002,029 MW2,255 MW
19 Sept, 07:002,081 MW2,358 MW
19 Sept, 08:002,189 MW2,460 MW
19 Sept, 09:002,244 MW2,518 MW
19 Sept, 10:002,325 MW2,510 MW
19 Sept, 11:002,307 MW2,545 MW
19 Sept, 12:002,357 MW2,573 MW
19 Sept, 13:002,285 MW2,443 MW
19 Sept, 14:002,309 MW2,298 MW
19 Sept, 15:002,357 MW2,310 MW
19 Sept, 16:002,216 MW2,363 MW
19 Sept, 17:002,407 MW2,521 MW
19 Sept, 18:002,581 MW2,593 MW
19 Sept, 19:002,680 MW2,645 MW
19 Sept, 20:002,624 MW2,572 MW
19 Sept, 21:002,451 MW2,489 MW
19 Sept, 22:002,275 MW2,353 MW
19 Sept, 23:002,172 MW2,221 MW
20 Sept, 00:002,057 MW2,067 MW
20 Sept, 01:001,919 MW1,958 MW
20 Sept, 02:001,792 MW1,938 MW
20 Sept, 03:001,758 MW1,958 MW
20 Sept, 04:001,748 MW1,942 MW
20 Sept, 05:001,758 MW1,958 MW
20 Sept, 06:001,755 MW1,980 MW
20 Sept, 07:001,813 MW1,970 MW
20 Sept, 08:001,851 MW2,035 MW
20 Sept, 09:001,830 MW2,013 MW
20 Sept, 10:001,808 MW1,987 MW
20 Sept, 11:001,649 MW2,017 MW
20 Sept, 12:001,821 MW2,087 MW
20 Sept, 13:001,951 MW1,937 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (686 of 686 hours in the window). Missing and zero values, and readings under 30% or over 3 times the grid's own median for the window, are treated as reporting faults and left out.
  • Error is (forecast minus reported demand) divided by reported demand; average error uses absolute values so high and low misses do not cancel. Bias keeps the sign and does cancel.
  • Reported demand is preliminary and may be revised. A 30 day window is a short sample and one heat wave or holiday can move these figures.
  • European figures are for the ENTSO-E bidding zone named on this page. US and European grids are ranked separately.